package com.linkstec;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class MapIteratorTest {
	//java 遍历map的四种方式  
	public static void main(String[] args) {    
	   
	    
	  Map<String, String> map = new HashMap<String, String>();    
	  map.put("1", "value1");    
	  map.put("2", "value2");    
	  map.put("3", "value3");    
	      
	  //第一种：普遍使用，二次取值    
	  System.out.println("++++++++++++++++++++++++++++++++++++++++++++==");
	  System.out.println("通过Map.keySet遍历key和value：");    
	  for (String key : map.keySet()) {    
	   System.out.println("key= "+ key + " and value= " + map.get(key));    
	  }    
	      
	      
	  //第二种：推荐，尤其是容量大时    
	  System.out.println("++++++++++++++++++++++++++++++++++++++++++++==");
	  System.out.println("通过Map.entrySet遍历key和value");    
	  for (Map.Entry<String, String> entry : map.entrySet()) {    
	   System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());    
	  }    
	  
	  //第三种    
	  System.out.println("++++++++++++++++++++++++++++++++++++++++++++==");
	  System.out.println("通过Map.entrySet使用iterator遍历key和value：");    
	  Iterator<Map.Entry<String, String>> it = map.entrySet().iterator();    
	  while (it.hasNext()) {    
	   Map.Entry<String, String> entry = it.next();    
	   System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());    
	  }   
	  
	  //第四种    
	  System.out.println("++++++++++++++++++++++++++++++++++++++++++++==");
	  System.out.println("通过Map.values()遍历所有的value，但不能遍历key");    
	  for (String v : map.values()) {    
	   System.out.println("value= " + v);    
	  }    
	 }    
}
